Construction of the $300 million North-South Tollway in Du Page County could force the cancellation of flood insurance policies for thousands of residents in communities along the East Du Page River, according to federal officials.
The tollway construction plans, unless changed, would both increase the river`s floodplain and make that expanded area more susceptible to flooding, said Stuart Rifkind, chief of the Natural Hazards Branch of the Federal Emergency Management Agency. This would be in violation of rules of the National Flood Insurance Program, which provides coverage to homes and businesses built within the flood plain.
The issue is crucial to Du Page, where high water is not uncommon, because the county has been declared a disaster area twice since 1970 because of flooding. The present tollway plans would both increase the area that could be flooded and mean that flood waters could rise a foot or more higher than in the past.
Although designers of the 17-mile tollway have planned the dredging of 23 water retention ponds to compensate for the paving and the rerouting of some creeks and streams, the rate of runoff from those ponds into natural waterways may be too rapid to prevent flooding, some experts say.
The federal agencies are exchanging information to determine the extent of the problem. If they find that the tollway will significantly aggravate flooding, portions of the road may have to be redesigned, possibly to include larger flood retention ponds.
The threat is so serious that the U.S. Army Corps of Engineers, which is preparing the required environmental impact statement for the road, recently met with FEMA and engineers for the State Toll Highway Authority in hopes of solving the problem.
”We set the standards to be in
the flood insurance program,” said Terry Reuss-Birman, a FEMA spokesman. She said failure to comply with those standards would result in the cancellation of the program in Du Page County.
Flood insurance, backed by the federal government, is sold by private insurance carriers to owners of homes and businesses.
The program is operated through contracts with each participating municipality and the county. Each jurisdiction must agree to prohibit development that will increase flood levels. In Du Page County, all municipalities and the county joined the insurance program after floods in 1972 caused extensive damage.
At a minimum, Reuss-Birman said, the East Du Page River flood plain would be significantly increased in size by construction of the tollway, forcing more homes and businesses into the federal flood insurance program.
Under the program, homes or businesses designated as being in a flood plain by the federal government aren`t required to have flood insurance until sold to a new owner. Subsequent owners are required to maintain the coverage, which costs in excess of $200 a year.
”If . . . it can be proven that there is no `practicable alternative` to this project, increases in the flood elevations may be allowed,” Rifkind said in his letter to the Corps of Engineers. ”However, the effects of increased flooding must be mitigated to the greatest extent possible and the affected flood insurance studies must be revised to reflect this new data.”
An executive order signed by President Jimmy Carter in 1977 requires an agency considering allowing development in a flood plain to ”consider alternatives to avoid adverse effects and incompatible development in the flood plain.”
The order requires the agency to ”design or modify its action in order to minimize potential harm to or within the flood plain.”
Major portions of the tollway are proposed to be built within or next to the flood plain of the East Du Page River.
The flooding issue initially was raised by the Morton Arboretum at an April public hearing held by the Corps of Engineers, which is to decide by August whether to issue a construction permit for the new road.
The State Toll Highway Authority plans to begin construction this fall on the tollway, which will parallel Ill. Hwy. 53 between Army Trail Road in Addison and Int. Hwy. 55 in Bolingbrook.
At the hearing, Marion Hall, arboretum director, said, ”The environmental impact statement concedes that the proposed North-South Tollway . . . may aggravate already severe flooding.”
Hall noted that the only storm used by the toll authority to calibrate its flood computer model for the Corps of Engineers impact statement occurred nearly 14 years ago. ”A significant amount of change has occurred in the watershed since 1972,” he said.
The Corps of Engineers study of the latest hydrology report submitted by the toll authority ”shows that the model flood profiles compare reasonably well” along the East Du Page River except at Prentiss Creek and St. Joseph Creek in Downers Grove.
At those locations the flood model being used by the authority predicts a 1.5- to 1.7-foot increase in the maximum flood level recorded in the federal flood insurance maps.
But Tom Slowinski, chief of the Corps of Engineers` regulatory functions branch, said the differences between the recent hydrology study and the existing federal flood maps occur because the maps in many cases are based on obsolete information.
The maps, according to Reuss-Birman, were prepared from 1975 to 1978, and in most cases haven`t been updated to reflect newer construction in the flood plain or to reflect increased water velocities caused by development at higher elevations.
Slowinski said accurate data will be turned over to FEMA to help it update the maps so a more accurate evaluation can be made of the tollway construction plans.
Concerns about flooding in Du Page County date to 1948, when damaging floods began occurring. Severe floods were reported in 1950, 1954, 1957, 1961, 1963, 1967 and 1972.
The county is prone to flooding because it is mostly a low-lying area interspersed with glacial moraines and large marsh areas. As development occurred, many of the marsh areas were drained and filled, increasing flooding problems.
In 1954, stores in Downers Grove along Main and Curtiss Streets had their basements and first floors flooded by overflow from St. Joseph Creek. In Lisle, the East Branch and St. Joseph Creek flooded, inundating Ill. 53 and several residential blocks.
The 1972 flood resulted in the county being declared a disaster area. That flood was estimated to be equal to one that would likely occur once in 50 years. Rainfall totaling more than 7 inches in three hours was reported in many county towns. State officials estimated damage to be in excess of $23 million.
